The present invention relates to integrated circuit (i.c.) fabrication methods and apparatus. In particular, the invention relates to methods and supporting apparatus to apply centered, perpendicular force to an integrated circuit package lid during the hermetic seal curing process interval.
Integrated circuits are frequently packaged for product assembly in sealed casements having only connector leads or points exposed for external conduit connection. Such packages are fabricated in laminated tiers with a dielectric base plate and a ceramic or plastic lid plate. Between the lamination tiers are two or more additional layers that route and electrically isolate electrical paths between specific circuit junctures on the integrated circuit chip and a corresponding connector lead or pin. The actual circuit chip is potted within a cavity surrounded by the laminations.
In the course of fabrication, as the laminations are added, vertically separated groups of connector leads are connected to the chip. Finally, the assembly is sealed by the addition of a cover or lid. Depending on the integrated circuit package type, the lid may be hermetically sealed by an epoxy adhesive or metallic solder, for example. Traditionally, the adhesive or solder is applied to either or both faces of the lid and substrate and cured or set while the lid is held down under a predetermined force applied by a spring clip. Unfortunately, excessive seal failures occur because of insufficient or inadequate distribution of seal force. These insufficiencies or inadequacies are perceived to arise from the lack of means to locate and direct the seal force along a central axis perpendicular to the lid plane.
It is, therefore, an object of the invention to provide a method for sealing an i.c. package lid that centers the sealing force normal to the lid plane.
It is also an object of the invention to provide a method which interfaces with an i.c. package assembly boat to uniformly locate the clip sealing force.
Another object of the present invention is to provide a method using a sealing load clip that may be reliably positioned at a predetermined location on an assembly boat and i.c. package lid.